The gelling process of organic-doped silica film fabricated by sol-gel technique was investigated by using in situ second harmonic generation (SHG) measurement.SHG signal came from the doped hemicyanine molecules which automatically oriented in the film.We found that the SHG measurement can be used as a semi-quantitatively probe of the gelling process.The time of gelling was found to depend sensitively on the annealing temperatures.Film shrinkage during gelling resulted in disordering of the doped hemicyanine molecules,consequently,SHG intensity decreased during annealing.